1. Field of the Invention
The present invention relates to a heat source shielding device for a hollow integration rod of a projecting apparatus.
2. Description of the Prior Art
The conventional projecting display apparatus can be a transmissive LCD, a reflective LCD, a digital micro device (hereinafter referred as DMD), or other available display components. Referring to FIG. 1, a schematic system diagram for a conventional projecting apparatus using a transmissive LCD projecting display apparatus in which an image formation device 16 is a projection lens. Such projecting apparatus consists of a reflection mirror 10, a light source 11, a first lens set 12, a hollow integration rod 13, a second lens set 14, a projecting display apparatus 15, an image formation device 16, and a display screen 17. The first lens set 12 includes at least one lens. The hollow integration rod 13 is an optical device provided with an incident light end 137 and an outgoing light end 138 to homogenize the light passing through it. The second lens set 14 includes at least one lens.
By means of the structure mentioned above, the light either directly transmitting from the light source 11 or being reflected from the reflection mirror 10 passes through the first lens set 12 and then converges on the incident light end 137 of the hollow integration rod 13. Afterward, the light being homogenized after passing through the hollow integration rod 13 passes through the second lens set 14 and reaches the projecting display apparatus 15 so that the image of the projecting display apparatus 15 is projected on the display screen 17 through the image formation device 16.
A conventional projecting display apparatus 15 shown in FIG. 2 is a DMD. The light once reaching the projecting display apparatus 15 is refracted to the image formation device 16 so as to project the image of projecting display apparatus 15 on the display screen 17.
A conventional projecting display apparatus 15 shown in FIG. 3 is the reflective LCD. The light after passing through the second lens set 14 and then reaching the projecting display apparatus 15 is reflected back to the second lens set 14 again and afterwards turns 90 degree toward the image formation device 16. Therefore the image of projecting display apparatus 15 is projected on the display screen 17.
FIG. 4 is a pictorial view of the hollow integration rod of the conventional projecting apparatus. As shown in FIG. 4, the hollow integration rod 13 consists of a first mirror 131 that is one set of two parallel mirrors with a reflecting film coated on one surface of each mirror and a second mirror 132 that is another set of two parallel mirrors with a reflecting film coated on one surface of each mirror. Thus a hollow rod is constructed with these two sets of mirrors by the adhesive 134 applied on the conjunction seams between mirrors wherein the internal surfaces of this hollow rod is constituted by the surface of every mirror coated with the reflecting film facing inward. The main function of the hollow integration rod 13 is to homogenize the light, after the light enters the incident light end 137 and reflects multiple times while passes through, emitting from the outgoing light end 138 and thereby to generate the homogenized projection picture.
At this moment the conventional projecting apparatus employs a light source of 120 Watt. The adhesive used for assembling the hollow integration rod 13 can sustain the temperature up to 120 degree centigrade while the surface temperature of hollow integration rod 13 is lower than 120 degree centigrade during the normal operation of projecting apparatus. However, along with the development of the projecting apparatuses, the light source used is increased up to approximate 150 Watt. Thus, during the normal operation of projecting apparatus, the surface temperature of hollow integration rod 13 is higher then 120 degree centigrade resulting in the collapse of the hollow integration rod due to the melting down of the adhesive.
In recent practice, in order to achieve the functional objective of homogenizing the light, only the portion of light reaching the incident light end 137 is required to transmit on the internal reflecting surfaces of the hollow integration rod 13 when the light transmits on the hollow integration rod 13. However, the rest portion of light not only is useless for achieving the functional objective but also creates the adverse effects resulted from the rest portion of light transmitting on the non-reflecting surfaces and the adhesive seams. One of the adverse effects is the melting down of the adhesive 134 due to the raise of the surface temperature of the hollow integration rod 13. This is the disadvantage of the hollow integration rod 13 of the conventional projecting apparatus.
Aiming at the disadvantage of the hollow integration rod of the conventional projecting apparatus, one of the objects of the present invention is to provide a heat source shielding device that utilizes a light reflecting metal shielding plate with the characteristic of excellent heat conductivity. The heat source shielding device is installed at an end of the hollow integration rod near the light source whereby all the light beams other than the ones transmitted into the opening at the incident light end impinge on the metal shielding plate. Furthermore, a relatively larger area for heat dissipation with better heat conductivity is utilized to conduct the heat generated by the light transmitting on the metal shielding plate. Then, a circulating air is produced by a fan in the projecting apparatus to remove the heat generated on the surface of the metal shielding plate due to convection. Thus, the surface temperature of the hollow integration rod is kept below 120 degree centigrade and consequently the adhesive, by which every mirror is adhered, is not melting down. As a result, the structural integrity of the hollow integration rod is therefore maintained.
In order to achieve the above mentioned objects, a heat source shielding device according to the invention for the hollow integration rod of the projecting apparatus is provided. The hollow integration rod consists of an incident light end and an outgoing light end while the heat source shielding device consists of a heat source shielding mask and a slip-on shell. The heat source shielding mask is an integrally formed metal sheet structure used for slipping onto the incident light end of the hollow integration rod. And the heat source shielding mask includes a first end, a second end, an end cover, a heat shielding plate, a first side plate, a second side plate, and a top plate. The slip-on shell is an integrally formed metal sheet structure with U-shape cross section used for slipping onto the outgoing light end of the hollow integration rod. And the slip-on shell includes a first end, a second end, a top plate, a side plate and a bottom plate provided with both a protruding plate near the first end for positioning and a stopper near the second end for halting the hollow integration rod.
Besides, the area of the top plate near the first end of the slip-on shell is overlapped and adhered by the heat conducting adhesive to the area of the top plate near the second end of the heat source shielding mask. Therefore, a portion of heat transferred from the heat shielding plate of the heat source shielding mask is dissipated through the slip-on shell by conduction. The rest heat accumulated in the heat shielding plate on the heat source shielding mask is yet dissipated by the ventilation system in the projecting apparatus due to convection.